Multi-disk shifting elements are used in motor vehicle transmissions, in particular automatic transmissions, as clutches and brakes for the shifting of gears. The actuation of the shifting elements, i.e. closing and opening, generally takes place hydraulically, whereas a separate hydraulic circuit with a transmission oil pump is provided. Upon closing the multi-disk shifting elements, due to friction, heat arises when pressing together the multi-disks—therefore, the shifting elements must be cooled in order to prevent an overheating and possible damage to the multi-disks or multi-disk coverings. For this purpose, supplying the multi-disk pack of the shifting elements with cooling oil from a lubricating oil circuit through suitable diverter valves is known. One problem with oil cooling of the multi-disks is that—in particular if there is an open clutch—the cooling oil between the multi-disks leads to an increased drag torque, which burdens the circuit of the lubricating oil pump and thus also the transmission efficiency.
Through DE 10 2005 007 685 A1, a cooling oil supply for a wet-running shifting element with a multi-disk pack is known. Thereby, depending on the position of the piston of the shifting element, the cooling oil is controlled mechanically, e.g. through a sliding plate affixed to the piston. Thus, in a closed state, the shifting element is constantly coated with cooling oil, which is slung to the outside against the shifting element by centrifugal force. In a further variant, a cooling oil flow is supplied to the multi-disk pack by actuating a valve, based on demand. Thereby, the cooling oil supply to the shifting element is carried out from the outside through an oil channel, whereas the valve is shifted on or off, based on demand.